The effect of fe-dopant concentration on ethanol gas sensing properties of fe doped ZnO/ZnO shell/core nanorods

• Fe-doped ZnO/ZnO shell/core nanorods were synthesized by encapsulation of bare nanorods.
• The nanorods morphology remained stable with Fe dopant and the crystallinity improved.
• Participation of Fe ions with +3 valences caused the electrical resistance to reduce.
• 5.0  at.% Fe dopant into shell layer enhanced the gas response.

In this paper, Fe-doped ZnO/ZnO shell/core nanostructures were synthesized through a simple two-step method and the effects of Fe dopant concentrations (between 0 and 9 at%) on the structural, optical, electrical and gas sensing properties were investigated. The X-ray diffraction analysis revealed that all of the samples are crystallized in the same wurtzite hexagonal crystal structure with (002) peak as the main orientation. Nevertheless, the morphology of shell/core nanorods remained stable with increasing of Fe dopant, but the crystallinity improved. The ultraviolet–visible spectroscopy analysis showed that the Fe ions have coordination number of 3+ in the ZnO shell layer. The participation of Fe3+ ions into ZnO layer was also confirmed by Current–Voltage (I–V) curves where the resistance of nanorods was reduced with Fe concentration. Moreover, the ethanol-sensing properties of the Fe-doped ZnO/ZnO shell/core nanorod sensors were systematically investigated. According to the results, optimum gas sensing was obtained by the addition of 0.5 at% Fe to ZnO shell layer which lead to significant enhancement in ethanol gas response.